Polymer dye and method for producing the same and its use in light-emitting diodes and other optical components

ABSTRACT

A method and apparatus for the removal of free, emulsified, or dissolved water from liquids of low volatility, such as oil, is shown. The liquid of low volatility is removed by contacting the fluid stream of concern with one side of a semi-permeable membrane. The membrane divides a separation chamber into a feed side into which the stream of fluid is fed, and a permeate side from which the water is removed. The permeate side of the chamber is maintained at a low partial pressure of water through presence of vacuum, or by use of a sweep gas.

BACKGROUND OF THE INVENTION

This invention relates to dicyanomethylene (DCM) based polymer dies andtheir production. These polymer dyes are used as red-emitting layers inorganic optical components, in particular in light-emitting diodes.

Organic luminescence displays and diodes can be produced on the basis oflow-molecular weight compounds which are transformed into light-emittinglayers by technically relatively complex evaporation coating processes.As a rule it is possible to set the wavelength of the light emitted bydosing the light-emitting layers with certain fluorescence dyes. Forexample, U.S. Pat. No. 6,048,630 describes saturated red emitting OLEDsthat are obtained by dosing Alq₃ with special porphine derivatives. Forthese materials, a strong emission is found at approximately 650 nm.U.S. Pat. No. 5,409,783 teaches magnesium phthalocyanine for dosing ofAlq₃ for red-emitting luminescence displays. A strong emission is foundat 692 nm.

The electroluminescence device has the following structure:

-   1. Transparent anode made of ITO coated glass-   2. Hole injection layer of Cu phthalocyanine (100 Å)-   3. Hole transport layer of poly-n-vinyl carbazole (600 Å)-   4. Emission layer of Alq₃ dosed with magnesium phthalocyanine-   5. Electron transport layer of Alq₃-   6. Cathode of Mg/ag (2000 Å).

The complete device structure is created by deposition processes. U.S.Pat. No. 5,908,581 describes the use of special laser dyes having thegeneral structure

for the dosing of the Alq₃ emission layer. The emission maximum is at616 nm. In addition to the complex technology of the construction of thedevice, the stability of such dosed emission layers must be viewedcritically. As a result of migration processes of the dosing agent oraggregation, there can be a shift of the emission spectrum. Thereforeorganic LEDs based on conjugated polymers have several advantages. Onone hand, these polymers, with suitable structural variations, can bedeposited from solution directly in the form of thin films byspin-coating or dip-coating. On the other hand, the active structure isessentially immobilized with regard to migration and aggregation by thebond to a polymer main chain.

Therefore, light-emitting LEDs with different emission wavelengths havebeen developed. In addition to blue and green shades, it became possibleusing alkoxy-substituted PPV derivatives (MEH-PPV) to realizewavelengths of 615 nm (DE 196 52 261). Wavelengths>650 nm have not up tonow been achieved by conjugated polymers.

Given these disadvantages of the prior art, the object of the inventionis to make available polymer dyes, the emission maximum of which is inthe red area of the spectrum. These materials must also be easy toprocess.

SUMMARY OF THE INVENTION

This object is accomplished by a polymer dye on the basis ofdicyanomethylene (DCM) having the general formula I

wherein R₁=H, straight-chain, branched or cyclic alkyl or alkoxy groupwith 1-20 C atoms, whereby R₁ can be bridged with R₂ by a ring of carbonatoms, R₂, R₃=independently of each other, H, straight-chain, branchedor cyclic alkyl or alkoxy group having 1-20 C atoms or aryl, whereby atleast one of the two groups is a group having the general formula II

wherein R₁, R₅=independently of each other, H, straight-chain, branchedor cyclic alkyl or alkoxy group with 1-20 C atoms, R₆, R₇=selectedindependently of each other, H, straight=chain, branched or cyclic alkylor alkoxy group having 1-20 C atoms, aryl, carbocyclic or heterocyclicgroup, whereby R₄ can be bridged with R₇ and/or R₅ with R₆ by a ring ofcarbon atoms, and at least one of the groups R₆ and R₇ represents apolymer backbone.

DESCRIPTION OF THE PREFFERED EMBODIMENTS

The invention teaches that a polymer dye is prepared on the basis ofdicyanomethylene (DCM) having the general formula 1.

In this case, R₁ is selected from the groups hydrogen, straight-chain,branched or cyclic alkyl or alkoxy groups having 1-20 C atoms, wherebyR₁ can be bridged with R₂ by a ring of carbon atoms.

R₂ and R₂ are selected independently of each other from the groupshydrogen, straight-chain, branched or cyclic alkyl or alkoxy groupshaving 1-20 C atoms or aryl, whereby at least one of the two groupsrepresents a group having the general Formula II

In this case, R₄ and R₅ are selected independently of each other fromthe group hydrogen, straight-chain, branched or cyclic alkyl or alkoxygroups having 1-20 C atoms and R₆ and R₇ are selected independently ofeach other from the group hydrogen, straight-chain, branched or cyclicalkyl or alkoxy groups having 1-20 C atoms, aryl, carbocyclic orheterocyclic groups. In this case, R₄ can be connected with R₇ and/or R₅with R₆ by means of a ring of carbon atoms. At least one of the groupsR₆ and R₇ must represent a polymer backbone, e.g. a polyester, apolyamide, a polyurea or a polyurethane.

The polymer dye preferably has an emission maximum between 620 and 680nm, with particular preference given to a maximum that lies between 640and 660 nm, i.e. in the saturated red area of the spectrum.

The at least one polymer group R₆ or R₇ is preferably bonded to the dyeby means of a hydroxyalkyl or aminoalkyl group. Particular preference isgiven to the use of a hydroxyethyl group.

The polymer dye preferably has a symmetrical structure. In that case,the groups R₂ and R₃ represent identical groups having the formula II.

Alternatively, however, it is also possible that one of the groups R₂ orR₃ is a group that is different from the one illustrated in Formula II,e.g. an alkyl group. In that case, the molecule in question isasymmetrical.

Preferably the two groups R₆ and R₇ represent identical polymer groups,e.g. polyester groups.

Alternatively, however, it is also possible that one of the groups R₆ orR₇ is a nonpolymer-forming group, e.g. an alkyl group.

The invention also teaches a method that has been developed for themanufacture of polymer dyes on the basis of dicyanomethylene (DCM),beginning with a malononitrile having the general Formula III

R₁ is thereby selected from the group hydrogen, straight-chain, branchedor cyclic alkyl or alkoxy groups having 1-20 C atoms. R₈ and R₉ areselected independently of each other from the group hydrogen,straight-chain, branched or cyclic alkyl or alkoxy groups having 1-20 Catoms, aryl, whereby R₁ can be bridged with R₈ by a ring of carbonatoms, and at least one of the groups R₈ and R₉ is a methyl group.

The method thereby proceeds according to the steps described below:

-   a) First, a condensation reaction with an amino benzaldehyde having    the general Formula IV is conducted.

In this case, R₄ and R₅ are selected independently from one another fromthe group hydrogen, aryl, straight-chain, branched or cyclical alkyl oralkoxy groups having 1-20 C atoms. R₁₀ and R₁₁ are selectedindependently from the group hydrogen, straight-chain, branched orcyclic alkyl or alkoxy groups having 1-20 C atoms, acyl, carbocyclic orheterocyclic groups, whereby R₄ can be bridged with R₁₁ or R₅ with R₁₀by a ring of carbon atoms, and at least one of the groups R₁₀ and R₁₁represents an amino or hydroxyalkyl group.

This condensation reaction results in a compound having the generalformula V

-   b) Then the compound having the general formula V is reacted with a    comonomer, e.g. a dicarboxylic acid, a dicarboxylic acid chloride, a    dicarboxylic acid anhydride or a diisocyanate and forms a polymer    having the general Formula I.

Preference is given to the use of a malononitrile having the generalFormula III, in which R₈ and R₉ represent methyl groups. On the basis ofthe approximately identical reactivity of the methyl groups in the 2 and6 position of the pyran ring, in addition to the formation ofmonocondensates, there is also an increased formation of bifunctionalcondensates.

Preferably, the bifunctional condensation products are thereby separatedchromatographically from the monofunctional condensation products.

It is also possible, however, to target the production of bifunctionalcondensates, because with a corresponding functionality they alsorepresent suitable polymer dyes for saturated red emitting polymermaterials. As a result of the elongation of the conjugation lengthcompared to the monocondensates, there is a significant red shift of theabsorption maximum.

Preferably, after the synthesis, the polymer dye is dissolved in asuitable solvent and processed into thin films. The solvent used ispreferably chloroform or cyclohexanone.

In an additional advantageous development of the method, in Step b), anadditional dihydroxide and/or diamino compound can be added to or atleast partly substituted in the compound having the Formula V.Particular preference is thereby given to the use of a compound havingthe general Formula VI

with X=OH or NH₂. The dye concentration in the resulting polymer can nowbe varied by means of these non-chromophoric dihydroxy or diaminocompounds. This may prevent the fluorescence extinction that may occurat high dye concentrations and improve the solubility of the copolymersas a result of the comonomer.

In this manner, the DCM dye content can preferably be set in theconcentration range between 0.5 and 100 mole per cent, and particularlypreferably between 5 and 40 mole per cent.

The object of the invention is explained in greater detail below withreference to the exemplary embodiments that are illustrated in theaccompanying diagrams, although the invention is in no way restricted tothe examples described or illustrated.

FIG. 1 shows the current-voltage characteristic of the polymer dye fromExample 7. The current (in Amperes) is thereby plotted against thevoltage (in Volts). This spectrum was recorded by bonding the electrodes(ITO and silver) and by then applying a negative potential too thealuminum electrode. A significant increase in the current was therebyobserved beginning at a voltage of approximately 15 V.

FIG. 2 shows a spectrum recorded analogous to FIG. 1 for the polymer dyefrom Example 5. This spectrum shows a significant increase of thecurrent beginning at a voltage of approximately 10 V.

FIG. 3 shows a plot of the luminous flux density of the device with thepolymer dye from Example 7 as a function of the voltage. In this casethere is a significant increase in the luminous flux density beginningat a voltage of approximately 15 V.

FIG. 4 shows the emission spectrum of the device with the polymer dyefrom Example 7. With regard to photoluminescence, the spectrum therebyhas a maximum at 645 nm, and a maximum for the electroluminescence at660 nm. This figure shows clearly that a red polymer emitter materialhas been produced that can be used in OLEDs.

Functionalized DCM-dyes

EXAMPLE 1 Manufacture of4-(dicyanomethylene)-2-methyl-6-(4-(bis-(2-acetyloxy)-ethyl)-aminostyryl)-4H-pyran

0.88 g of (2,6-dimethyl-4H-pyran-4-ylidene)-malononitrile and 1.47 g of4-[bis-[2(acetyloxy)ethyl-amino] benzaldehyde are reflux-boiled in 75 mlof toluene with the addition of 20 drops of piperidine for 18 hoursunder N₂. The solution is concentrated in the rotary film evaporator.The residue is dissolved in 20 ml of acetone and precipitated in 200 mlof water. The educts and other highly volatile impurities are removedfrom the raw product, which has been drawn off and dried, by sublimationat 2*10⁻³ mbar and 90° C. The other impurities (essentially the biscondensate) are removed by flash chromatography (silica gel, ethylacetate/hexane 1:1). 0.7 g (22%) of pure product is obtained.Elementary Analysis:

Element Contents (theoretical) Contents (measured) N 9.39 9.42 C 67.1066.95 H 5.63 5.55Result ¹³C-NMR in acetone-d₆:

d in ppm: 171.730 (C23 and C30); 164.775 (C6); 162.515 (C 12); 158.168(C4); 151.133 (C8); 131.436 (C10 and C14); 124.855 (C9); 116.744 (C17and C26); 114.879 (C7); 113.604 (Cl 1 and Cl 3); 196.976 (C5); 106.670(C3); 62.514 (C21 and C28); 57.602 (Cl 5); 50.838 (C20 and C27); 21.421(C31 and C32); 20.401 (C18)

EXAMPLE 2 Manufacture of4-(dicyanomethylene)-2-methyl-6-(4-bis-(2-hydroxyethyl)-aminostyryl)-4H-pyran

0.57 g of4-(dicyanomethylene)-2-methyl-6-(4-(bis-(2-acetyoxy)-ethyl)-aminostyryl)-4H-pyran,to which 2.5 ml of 5% NaOH is added, is stirred in 25 ml of methanol for2.5 hours at 40° C. under nitrogen. After cooling, the precipitateobtained is filtered, washed with methanol and dried. 0.33 g of product(72%) is obtained.

Element Contents (theoretical) Contents (measured) N 11.56 11.16 C 69.4169.25 H 5.82 5.89

EXAMPLE 3 Manufacture of4-(dicyanomethylene)-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl-4H-pyran

2 g of (2,6 2,6-dimethyl-4H-pyran-4-ylide)-malononitrile and 4.37 g ofN-methyl-N-(2-hydroxyethyl)-4-aminobenzaldehyde were placed in 30 ml ofn-butanol. After the addition of approximately 1 ml of piperidine, thesolution was reflux boiled for 12 hours. After cooling, the precipitatewas drawn off and washed twice with a small amount of methanol. The rawproduct was decocted with 50 ml of methanol, cooled, drawn off anddried. 4.56 g of chromatographically pure4-(dicyanomethylene)-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl-4H-pyran(yield 79%) was obtained.

Result of the Elememtary Analysis:

Element Contents (theoretical) Contents (measured) N 11.33 11.37 C 72.8572.17 H 6.11 6.47Result ¹³C-NMR in DMSO-d₆:

d in ppm: (160 (C4); 156 (C2 and C6); 151 (C12 and C23); 139 (C8 andC19); 130 (C7 and C18); 122 (C10, C14, C21 and C25); 116 (C9 and C20);113 (C6 and C28); 111 (C11, C13, C22 and C24); 105 (C3 and C5); 58 (C33and C36); 54 (C32 and C35); 53 (C15)?; 39 (C27 and C31); 31 (solvent ?)

Polymer Syntheses with DCM Dyes

EXAMPLE 4 Polyester Synthesis from the Dye in Example 3 and isophthalicacid dichloride

0.495 g of4-(dicyanomethylene)-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl)-4H-pyranwere dissolved in 10 ml DMF+5 ml pyridine. 0.2039 g of isophthalic aciddichloride in solution form was added a drop at a time to 5 ml DMF whilestirring. After 4 hours at room temperature, the polyester wasprecipitated in 650 ml methanol. The precipitate was drawn off, washedseveral times with methanol and dried in a vacuum. The result was 460 mgof polyester (74% yield). For further purification, the polymer wasdissolved in 50 ml DMAc, the insoluble components were filtered out,precipitated in 500 ml methanol, drawn off, washed with methanol anddried in a vacuum.

Result of Elementary Analysis:

Element Contents (theoretical) Contents (measured) N 8.97 8.89 C 73.0669.43 H 5.16 5.50Result ¹³C-NMR in DMSO-d₆:

d in ppm: 167 (cannot be classified); 166 (C33 and C44); 161 (C4); 157(C2 and C6); 152, C12 and C22); 139 (C8 and C 18); 134.5 (C41 and C43);131 (C39); 130.5 (C7, C18 and C42); 130 (C38 Lind C40); 124 (C 10, C14,C20 and C24); 117 (C9 and C 19); 114 (C 16 and C27); 112 (C 11, C 13,C21 and C23); 106 (C3 and C5); 63 (C31 and C36); 59.5 (C in theneighborhood of free OH-groups?); 55 (C30 and C35); 51 (C 15); 39 (C26and C29)1

EXAMPLE 5 Polyester from the Dye Described in Example 3 and2.5-di-(2-ethylhexyloxy)-terephthalic acid dichloride:

0.4946 g4-(dicyanomethylene)-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl)-4H-pyranwere dissolved in 10 ml DMF and the2,5-di-(2-ethylhexyloxy)-terephthalic acid dichloride (0.4594 g) wasadded a drop at a time at room temperature to 5 ml DMF+5 ml pyridinewith agitation. After 2.5 hours, the polymer was precipitated in 500 mlmethanol. The polymer was drawn off, washed with methanol and dried in avacuum. The yield was 560 mg (64%). For purification, the polymer wasdissolved in 30 ml of chloroform and precipitated in 300 ml of methanol.It was drawn off and again dissolved in 30 ml of chloroform andprecipitated in 300 ml of hexane. The purified product was dried in avacuum.

Result of Elementary Analysis:

Element Contents (theoretical) Contents (measured) N 6.36 6.45 C 73.6170.78 H 7.32 7.04Result ¹³C-NMR in CDCl₃:

d in ppm: 166 (C33 and C51); 159 (C4); 156 (C2 and C6); 152 (C12 andC22); 150 (C39 and C42); 138 (C9 and C18); 130 (C7 and C17); 124 (C38and C41); 123 (Cl 0, C14, C20 and C24); 116,5 (C9 and C19); 116 (C40 andC43); 114 (C16 and C27); 112 (Cl 1, C13, C21, and C23); 105 (C3 and C5);72 (C45 and C54); 62 (C31 and C36); 54 (Cl 5); 50 (C30 and C35); 39.5(C46 and C55); 39 (C26 and C29); 30 (C47 and C56); 29 (C48 and C57); 24(C50 and C62); 23 (C49 and C58)i 14 (C50 and C59); 11 (C61 and C63).

EXAMPLE 6 Polyurethane from the Dye Described in Example 3 and4,4′-methylene-bis-(phenyl isocyanate) (MDI)

0.4946 g of4-(dicyanomethylene-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl)-4H-pyranwere added in the form of a solution in 20 ml DMF under an N₂ atmosphereto a solution of 0.2503 g MDI in 5 ml DMF. First the solution wasstirred at room temperature for 3.5 h. Then the temperature wasincreased to 70° C. and stirred for an additional 2 hours. The solutionwas precipitated in 300 ml methanol+100 ml hexane. Then it was drawnoff, washed with methanol and dried in a vacuum. The yield was 0.71 g(74%). For further purification, the polyurethane was dissolved in 30 mlDMF and again precipitated in 300 ml methanol+100 ml hexane.

Result of Elementary Analysis:

Element Contents (theoretical) Contents (measured) N 11.28 12.35 C 72.5666.34 H  5.41  6.14Result ¹³C-NMR (DMF-d7):

161 (C4); 157 (C2 and C6); 154.5 (C33 and C53); 151 (C12 and C22); 139(CS and Cl 8); 138 (C42 and C46); 137 (C39 and C49); 131 (C7 and Ci 7);130 (C41, C43, C47 and C51); 124 (C10, C14, C20 and C-24); 119 (C40,C44, C48 and C50); 117 (C9 and Cl 9); 114 (Cl 6 and C27); 112.5 (Cl 1,Cl 3, C21 and C23); 105.5 (C3 and C5); 62.5 (C31 and C36); 55 (Cl 5);51.5 (C30 and C35); 41 (C45); 39 (C26 and C29).

EXAMPLE 7 Co-polyurethane from the Dye Described in Example 3,4-4′-methylene-bis-(phenylisocyanate) and N-phenyl-diethanolamine:

0.4946 g of4-(dicyanomethylene-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl)-4H-pyran(1 mmol) and 0.7249 g of (4 mmol) N-phenyl diethanoldiamine weredissolved under an Ar atmosphere in 60 ml of DMAc. After the addition of1.2513 g (5 mmol), 4,4′-methylene-bis-(phenylisocyanate), the solutionwas heated to 80° C. and stirred at this temperature for 5 hours. Thepolymer was precipitated in a mixture of 600 ml methanol and 200 mlhexane. The precipitate was dried in a vacuum. For further purification,it was dissolved in THF, precipitated in 200 ml hexane, drawn off anddried in a vacuum. 1.09 g (44%) of the copolymer were obtained.

Result of the Elementary Analysis

Element Contents (theoretical) Contents (measured) N 10.05 10.13 C 70.1869.25 H 5.75 6.33Result ¹³C-NMR (DMF-d7):

All the signals of the monomers are present. The signal of the urethanehydrocarbon at 154.5 ppm was also found. From the ratio of the signalsof the monomers, a molar copolymer composition of MDI=1, N-phenyldiethanoldiamine=0.64 and DCM-A-derivative=0.36 was calculated.

EXAMPLE 8 Co-polyester from the Dye as Described in Example 3,2,5-di-(2-ethylhexyloxy)-terephthalic acid dichloride and N-Phenyldiethanol amine

0.1978 g of (0.4 mmol)4-(dicyanomethylene)-2,6-bis-(4-(N-2-hydroxyethyl-N-methyl)-aminostyryl)-4H-pyranand 0.2800 g N-phenyldiethanol amine (1.6 mmol) were added to 20 mlDMAc. The 2,5-di-(2-ethylhexyloxy)-terephthalic acid dichloride (0.9179g) was added dropwise in the form a solution to 5 ml DMAc while beingstirred at room temperature. After 14 hours, the solution wasprecipitated in 500 ml methanol. It was drawn off and dried at 50° C. ina vacuum. 0.38 g (59%) of the copolyester was obtained.

Result of the Elementary Analysis:

Element Contents (theoretical) Contents (measured) N 3.25 3.30 C 72.2771.01 H 8.42 8.45Result ¹³C-NMR (DMF-d7):

All the signals of the monomers are present. The signal of the esterbond is also found at 165.5 ppm. From the ratio of the signals of themonomers, a molar copolymer composition of2,5-di-(2-ethylhexyloxy)-terephthalic acid dichloride=1,N-phenyldiethanol diamine=0.81 and DCM derivative as described inExample 3=0.19 was calculated.

Production of the Device

EXAMPLE 9

PLEDs are produced using the general method outlined below. This methodmust naturally be adapted in the individual case to the respectiveconditions (e.g. polymer viscosity, optimal layer thickness of thepolymer in the device etc.). The PLEDs described below are single-layersystems, i.e. substrate/ITO/polymer/cathode.

From the polymer described in Example 7, a solution was prepared with aconcentration of 3-25 mg/ml in THF, DMF and chloroform at roomtemperature. For the manufacture of the electroluminescence device, thepolymer was dissolved in THF and solutions in the concentration range of0.25% to 1% were prepared. The preferred range is thereby between 0.6%and 0.8%.

From the polymer described in Example 5, a solution was prepared with aconcentration of 5-20 mg/ml in THF, DMF and chloroform at roomtemperature. For the manufacture of the electroluminescence device, thepolymer was dissolved in chloroform and solutions in the concentrationrange of 0.25% to 1% were prepared. The preferred range is therebybetween 0.7% and 0.9%.

Depending on the polymer, it may also be advantageous to agitate thesolutions for some time at 50-70° C. or to treat them in an ultrasoundbath.

Before the spin-coating of the polymer solution on an ITO-coated glasssubstrate (Balzers) approximately 25 cm², a polymer intermediate layer(BAYTRON®) is deposited for the matching of the injection barriers.

The polymer solution in Example 7 was purified through a 1 μm sprayfilter prior to the spin-coating. Then the polymer layer was depositedwith a thickness of approximately 100 nm. The layer was tempered underinert conditions at 110° C. for 2 hours.

The polymer solution described in Example 5 was purified through a 1 μmspray filter before the spin-coating. Then the polymer layer wasdeposited with a thickness of approximately 100 nm. The layer wastempered under inert conditions at 110° C. for 2 hours.

The layer thicknesses can be varied by means of the spin-coatingparameters between 30-200 nm. Then the cathode consisting of a thinlayer of calcium (approximately 30 nm) and a silver layer (approximately100 nm) was evaporated.

After the electrodes (ITO and silver) had been placed in contact and anegative potential had been applied to the aluminum electrode, theelectrical and optical characterizations illustrated in FIGS. 1 to 3were performed.

1. A polymer dye on the basis of dicyanomethylene (DCM) having thegeneral formula I

wherein R₁=H, straight-chain, branched or cyclic alkyl or alkoxy groupwith 1-20 C atoms, whereby R₁ can be bridged with R₂ by a ring of carbonatoms, R_(2,) R₃=independently of each other, H, straight-chain,branched or cyclic alkyl or alkoxy group having 1-20 C atoms or aryl,whereby at least one of the two groups is a group having the generalformula II

wherein R₄, R₅=independently of each other, H, straight-chain, branchedor cyclic alkyl or alkoxy group with 1-20 C atoms, R₆, R₇=selectedindependently of each other, H, straight=chain, branched or cyclic alkylor alkoxy group having 1-20 C atoms, aryl, carbocyclic or heterocyclicgroup, whereby R₄ can be bridged with R₇ and/or R₅ with R₆ by a ring ofcarbon atoms, and at least one of the groups R₆ and R₇ represents acopolymer backbone, producible by copolymerization of a first comonomerselected from the group consisting of: dicarboxylic acids, dicarboxylicacid chlorides, dicarboxylic anhydrides and diisocyanates; and a secondcomonomer selected from the group consisting of: dihydroxy and diaminocompounds.
 2. The dye as claimed in claim 1, wherein the emissionmaximum lies between 620 nm and 680 nm.
 3. The dye as claimed in claim1, wherein at least one of the polymer groups R₆ and R₇ is bonded to thedye by a hydroxyalkyl or an aminoalkyl group.
 4. The dye as claimed inclaim 1, wherein at least one of the groups R₆ and R₇ is an alkyl group.5. The dye according to claim 1, wherein the polymer backbone is abackbone of one of copolyesters, copolyamides, or copolyurethanes. 6.The dye according to claim 2, wherein the emission maximum lies between640 and 660 nm.
 7. The dye according to claim 3, wherein thehydroxyalkyl or aminoalkyl group bonding at least one of the copolymergroups R₆ and R₇ is a hydroxyethyl group.
 8. The dye according to claim1, wherein the at least one of the groups R₂ and R₃which is an alkylgroup is a methyl group.
 9. The dye according to claim 4, wherein the atleast one of the groups R₆ and R₇ which is an alkyl group is a methylgroup.